Recombination exchange of genetic material between

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Unformatted text preview: mutation 2. recombination (exchange of genetic
material between homologous chromosome during meiosis) 3. epigenetic modification of
genome (that do not involve in changes in nucleotide sequence) 4. more recently, during
embryonic development, the environment can modify the phenotype, this selection can act on
this phenotypic variation (this is call developmental plasticity). this is particularly important in
development of nervous system 1. Species produce more offspring than resources can support 2. Individuals vary in ability to compete for resources, survive,
and reproduce (variation)
3. Some of this variation is heritable (inheritance)
4. Differences in survival and reproduction lead to overrepresentation of more successful forms in next generation
(selection)
5. Selection over generations leads to change in composition of
the population (evolution)
darwin's genius is to draw the next 2 conclusion from the first 3 observation:
4. this is the process of natural selection. natural selection is different from artificial
selection (done purposely by breeders of domestic plants or animals
5.over time, selection operate repeatedly on successive generation to produce
changes in composition of population. Natural Selection ≠ Survival of the Fittest*
*Herbert Spencer (1894) • Selection maximizes reproductive
fitness, not health or longevity
• Evolutionary success of humans
did not require a “long” life let's begin discussion first by correcting misconception:natural selection do NOT mean survival of the fittest. Life expectancy (Years) -natural selection optimizes reproductive fitness. strength and health may be part of reproductive fitness, but
natural selection don't care. it only cares about survival of genes. 80
70
60
50
40 -but an important question to ask would be "is long life part of reproductive strategy in human?"
-well, the answer is no. the graph show that starting at 1800s, life expectancy is around 30. then life expectancy
dramatically increase probably due to nutrition, hygiene, and medical adv...
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